The translation of the sickle mutation into clinical disease involves and exceedingly complex pathophysiology. This Program is based on the concepts that vascular endothelial cell biology is central to the vascular pathobiology of sickle disease, and that sickle disease comprises an inflammatory state with abnormal endothelial cell activation/dysfunction: This Program focuses on important issues related to these concepts. Technologies employed range from physiology and clinical investigation, to cellular biology and biochemistry, to molecular biology. The Program has three cores: Administrative (A), Cell Culture (B), and Transgenic Mouse (C). Project 1 focuses on abnormal tissue factor expression by pulmonary vein endothelium, and the roles of inflammation and NO and reperfusion injury in this process. Studies to be done will include use of various knockout states bred into the sickle animal, as well as specific cell types isolated from knockout mice. Project 2 examines white blood cell interaction with the endothelium in the live sickle transgenic mouse. The role of sickling in causing inflammation will be evaluated, and the role of adhesive white cells in causing secondary red cell occlusion will be studies. Roles of NO and prostaglandin will be defined. Project 3 will use a model of regional ischemia (kidney) to study the process by which hemeoxygenase- 1 (HO1) modifies response to ischemia, looking at adaptive and maladaptive changes. Studies to be done will include use of mice with conditional HO1 knockout state. Project 5 focuses on the role of HO1 in modulating vascular stasis in the sickle mouse. Studies to be done include use of the HO1 overexpressing sickle mouse. In conducting these Projects, our overarching objective is to achieve a greater understanding of disease pathobiology as a path to identifying novel therapeutic approaches to this disease. Lay Summary: Sickle disease is a severe disease that causes premature death and many health problems. Our studies are designed to understand how this disease works. We believe that the results of our proposed studies will directly lead to new treatments for sickle patients.